| Another common problem: You've got a video recorder (or similar) connected in line and you've left it switched on. Its RF output is blocking a Freeview multiplex. Other problems - typically "no signal" or "picture breaks up into squares" may be caused by the VCR or by insufficient signal or by interference getting into the aerial system (which includes the aerial, the downlead and anything connected in it). Interference | 
| Interference is radiated by electronic equipment such as DECT phones, lamps, electric fences, energy-saver lamps, computers, wireless routers, microwave ovens, videosenders, laptops, DVDs, TV sets ... and can affect other electronic equipment - especially equipment that is designed for receiving extremely weak signals. (If you don't believe this, try holding an AM radio next to them!) The interference is usually strongest behind the TV set so you must ensure that all coaxial "fly-leads" and wall plates are fully shielded, otherwise the inteference gets carried back into the Freeview or TV tuner! |
If you think you have problems of interference, move the Freeview receiver well away from the TV set (a source of interference), and the VCR/DVD, and switch off all other equipment in the house, including TV sets, DVD players, fluorescent and energy-saver lights, electronic insect frighteners/killers, computers and central heating. (Dimmer switches can cause problems). If this gets rid of the problem, switch everything back on, one by one, to track down the cause. If it's a thermostatic switch or an ordinary switch, it may be possible to fit a suppressor. If the source of interference can't be traced that way, see if you can hear it on any waveband on a portable radio or TV set. Tune it off-channel until you can hear the interference. Then walk around to see if you can pinpoint the direction. It could be a street lamp (common) or something in a neighbour's house. You need to determine where the interference is getting into your aerial system. This is far from easy so all you can do is take "belt and braces" measures to prevent it. - Mount the aerial as far from sources of interference as possible.
- Use fully-shielded aerial wall-socket (if used).
- Use fully-shielded coax and run it as far from electrical cables as possible (never alongside them).
- Fit suppressors to equipment that is known to be causing problems.
- Make sure you have adequate signal in the cable by using a very low noise masthead amplifier as close to the aerial as possible and an equivalent attenuator at the aerial-input of the receiver.
- Various types of filter are available which might help.
Tropospheric Propagation At certain times of year you may receive interference from transmitters which are hundreds of miles away. Sometimes, for example, people in Essex can do a scan and tune in broadcasts coming from (say) Winter Hill in the North West, or from Holland. There is seldom a cure for this and it usually lasts for only a few hours a day for up to a week. DO NOT RESCAN while this is happening! The last thing you want is for your receiver to memorise foreign stations. Has it never worked properly? - Are you using the correct aerial for your location?
- Is it outdoors? Is it aligned on the correct transmitter?
- Is your Freeview receiver a good one? (Some cheap modern ones have very poor tuners that require a strong aerial signal. You can waste a lot of money on aerial systems when it's your cheap supermarket receiver or digital TV that's at fault!)
- Is the signal strength correct? While analogue TV is still broadcast, the analogue signal is much stronger than the digital signal. The result is that, if your digital signal strength is high, the analogue will be even higher. In some areas, having the digital signal higher than 50% means that the analogue signal will be strong enough to "blind" your digital tuner, so the weakest stations may not be receivable. However, don't be fooled by a low signal reading. If the analogue signal is way too high, it can cause the digital tuner to "wind down its gain factor", causing the signal reading to appear very low or to "bounce"! You really need to get an expert opinion on the correct signal strength for your location. If it's too high, you may need to fit an attenuator. (A signal reading over 60% is questionable. Over 80% is likely to be too high).
- Is everything screened? Make sure the wall plate is fully shielded. Make sure any fly-leads use double-screened cable. Make sure your downlead from the aerial is the double-screened type with no kinks or intermediate connections.
- If that's OK, maybe you need a better aerial or maybe a booster will help. Click HERE for information about aerial boosters and connecting to more than one TV set or Freeview box.
To get a FREE report on Freeview reception at your postcode location, click HERE. Need a good indoor aerial? Click HERE. Need more help? Contact us with your full postcode, complete description of your equipment (makes and model numbers) and details of the problem plus the results of all the checks we have suggested on this page. Daytime/nightime difference? The Freeview signal strength drops slightly during the hours of daylight. If you have good reception at night but poor during the day, it's most likely that your aerial system is marginal. Check out everything mentioned above relating to correct aerial, cable, wall plate etc. If your reception is worse at night then your signal may be too strong or you may be suffering from local electrical interference. Wet leaves or wet tiles If your reception deteriorates during falling rain, the cause is likely to be wet leaves or wet tiles in the signal path. Rain by itself can also have an effect on reception if it is very heavy. Indoor Aerials Note: indoor aerials are notorious for causing problems because the signals can be reflected by nearby walls, roof tiles, pipes, wiring and even human bodies! The result can be signal cancellation, causing complete or partial loss of some channels. The positioning of the aerial can, therefore, be extremely critical. Even after you've got it "right", if something gets moved (even a metal object next door) the signal could be affected. Because of signal reflections and interference, the positioning of an indoor aerial is absolutely critical. An inch can make the difference between receiving all channels perfectly or none. (Each time you move the aerial during setup you must rescan the channels. Once you've got all the channels, do not rescan!) I'd start by keeping the aerial as far from sources of interference as possible. The major source of interference is the TV set itself. (How many times have you seen an aerial perched on top of the TV and "wavy lines" on the picture?) Other sources of interference include electrical wiring and electrical equipment - especially equipment fitted with a thermostat. So don't do the ironing next to the aerial! Placing the aerial on top of (or above) a metal structure can sometimes help. Try a metal CD rack or a (cold) radiator. Try varying the height. In a bedroom, on top of a wardrobe is often a good choice. Try putting aluminium foil on the wall behind the aerial to reflect the signal. (The results are unpredictable but it sometimes helps). If possible, aim the aerial through a window or (if in a loft) through tiles not brick. This is pretty obvious but most people overlook the fact that solid materials attenuate the signal. So, you have three main factors to deal with: - Attenuation of signal due to material in the way
- Cancellation of signal due to out-of-phase reflections
- Interference from mains wiring and electrical/electronic equipment
If you can't get all channels with an indoor aerial, try this: Connect your Freeview receiver temporarily to a better aerial pointing at the same transmitter. Run a channel search and make sure all the channels are stored. Now reconnect the indoor aerial and move the aerial to get as many channels as possible. DO NOT RESCAN. If you later lose some channels DO NOT RESCAN. Move the aerial until you get them back. (If you rescan while the signal is too weak, the receiver will "forget" the weak channels). Why does it work like this? A Freeview receiver will only store a multiplex if the signal is somewhat higher than the tuner minimum "threshold". If the signal is too low, the Freeview box will see it but will not store it. However, if you give it a nice strong signal, the multiplex position will be stored and remembered. Provided that the weaker signal is above the tuner threshold value, you'll be able to watch the programmes. Note, however, that they are likely to be more stable at certain times of day (usually after dusk) and that, at some times of day, the picture or sound may "break up". Loft aerials can be troublesome because they are so close to house wiring, human bodies in the bedroom, water tank (reflections), roof (attenuates signal - especially when wet). Make sure that the roof is not lined with a reflective metallic layer! Arrange the aerial so it is pointing through tiles, not bricks. The centre of a loft is often the worst position because interference tends to be concentrated there. Make sure that cable is fully shielded type and does not run parallel to any mains cables. If the aerial itself is picking up interference then you might be able to shield it with a "ground plane" at least 0.5m below it. However, the chances of success are small. If the cable is picking up interference then try amplifying the signal from the aerial with a very low-noise masthead amplifier and attenuating it at each receiver. What's the best indoor aerial? For lots more information including choice of aerial, installing an aerial, read our "Freeview Bible". To email us for specific help regarding your Freeview reception, please click HERE. | 
